Core-shell magnetic nanoparticles with surface-imprinted polymer coating as a new adsorbent for solid phase extraction of metronidazole

We have prepared a nanoparticle-based metronidazole-imprinted polymer by combining a surface molecular imprinting technique with a sol-gel process. Metronidazole was used as a template, 3-aminoprophyltriethoxysilane as the functional monomer, and tetraethyl orthosilicate as the cross-linker. The resulting magnetic molecularly imprinted polymer was characterized by Fourier transform infrared spectroscopy, powder X-ray diffraction and scanning electron microscopy. The adsorbent can be applied to the solid phase extraction of metronidazole and exhibits high adsorption capacity, good selectivity, favorable reusability and the feature of magnetic separation. The binding performances of the adsorbent were evaluated by equilibrium rebinding experiments and Scatchard analysis. The material was successfully applied to solid phase extraction of metronidazole, followed by spectrophotometric determination in food samples. Spiked recoveries ranged from 88.5% to 97.0%, with relative standard deviation (RSD) of <3.5% for milk samples, and of 85.6% to 96.0% (with RSDs of 3.3-4.5%) for honey samples.